Ah, springtime in the northern latitudes brings a welcome relief from winter. Grass starts popping up and horses start doing impressive equine yoga trying to reach each fresh little blade under fences.
However, if you have a horse deemed an “easy keeper”, or worse, with a diagnosed condition such as Equine Metabolic Syndrome, insulin resistance (IR), or Cushing’s disease, this time of year heralds the start of a difficult struggle. Grass, the succor of all horses, can be your worst enemy, but brings such contentment to the ponies. Managing grazing is complex and highly dependent on environmental conditions. This blog is about my own struggle with grass grazing and some botanical facts that are not well known that profoundly impact on your fat horses’ health and ability to graze your IR/EMS horse.
My mare Tess is a quintessential cobby Andalusian/Arab cross mare. Even on her skinny jean days she is round and shapely- the Mae West of the horse world. While I try to rationalize her body (big boned, round butt), truth is most of the time I have to search a bit for ribs with moderate pressure over the ribcage. There is no rationalizing this fact.
I used to keep my two horses together in the same dry. They are at the opposite ends of the eating spectrum- my gelding Tomax picks at his food all day, eating on and off, is a good self-exerciser, and on his “fat” days looks like a fit horse. Tess makes a career out of standing in the same spot, and I have at times considered re-naming her Hoover. After one winter penned together Tess started resembling a beach ball and seemingly overnight developed an impressive stallion crest. This was four years ago, and I had blood pulled, fingers crossed. Now here is the interesting thing—she didn’t test positive for IR or Cushings although she had suspicious looking fat pads over her neck, shoulders, and tail head. She went on a strict diet and increased exercise. She slimmed down by about 250 lbs. and was back to her Jennifer Lopez shapely booty. I sucked it up and built a fence in my dry lot and separated the two horses. Over the years, I have kept tabs on her endocrine system via blood tests- and sure enough, despite RIGOROUS management and keeping her near target weight, she slowly developed the true clinical signals that her body told me all along: insulin resistant, Cushing’s positive by 14 years old. During this journey of blood tests she never foundered, has had many skinny-jean months, but she just had “the look”. Take home message: trust your gut, even if the blood tests say otherwise, because sometimes it takes years for clinically detectable disease indicators to develop. Even more interestingly, she has never tested positive for hypothyroidism, so the general protocol of putting her on Thyro-L without a blood test (seeming a popular thing to do in some places for overweight horses) would never have been the answer. In my next blog I will discuss actual feeding protocols, but this article is all about the green stuff.
In today’s burgeoning suburbia, unlimited grazing that would satisfy all the horse’s needs is becoming a rarity, and grass is more an appetizer to a main course of conserved feeds such as hay and cubes. Nevertheless, an appetizer of grass at the wrong time is all it could take to send the horse into a laminitic episode. Alarmingly, a laminitic episode can occur more than a week after a bout of overgrazing .
Now about grass.
Not all grass is created equal. For the purposes of this article, I am discussing cool season grasses- those grasses that grow in places that have killing frosts and well defined four seasons- pretty much many of the temperate latitudes of North America/Europe/Asia. The adaptations of these grasses to the cold season is what makes them so tricky for horse owners to feed.
The tricky part of cold season grasses is the sugar- specifically fructans. Fructans are the simple sugars that the plant uses for energy. Fructans are produced during photosynthesis during daylight hours and stored for use during nights [2, 3]. Fructan concentration in the grass can vary greatly depending on type of grass, temperature, moisture, and season [2, 3]. Cool season grasses found in areas with actual winters are the strong fructan producers. When the plant is high in fructans, it is like feeding a Type 2 diabetic a candy bar- it causes a big spike in insulin, which has a variety of negative effects, not the least of which is vasodilation in the laminar tissues of the feet (one reason sugary grass in implicated in chronic laminitis).
In general, fructan levels spike in grass due to the following environmental conditions :
1. When there are low nighttime temperatures and warm day temperatures (big temperature differential)
2. When there are bright, sunny, warm days where plants are actively photosynthesizing
3. When the plants are in the active growing stage
4. When there is hot, dry drought stress, the fructans concentrate in the stem
5. Anytime the plant is stressed- like by overgrazing.
Think about this—for myself, living in the Northern Rockies, if I want to safely graze my IR horse, I need to do it when it’s not sunny, when the nights and days are both relatively warm, when the grass plant is not actively growing, and when there is not a serious dry spell. That rules out spring and fall (cool nights, warm days, and actively growing plants) and much of summer (hot and dry) - in other words, pretty much the entire non-winter time of year. It’s downright depressing for me, with my four luscious acres of grass, and even more so for my mare. What to do?
Here is how I manage my IR horse.
1. Monitor digital pulses. BEFORE there is a crisis, learn to take your horse’s resting digital pulse (this is the pulse down by the feet). Ask your vet or a knowledgeable horse friend to help you find this. Feeling the pulse “tone”- pressure, strength is as important as the actual count. A strong bounding pulse (which could indicate potential onset of laminitis) may not be dramatically faster, just much stronger.
2. Introduce grass slowly and at the right times. I actually keep my mare off the grass until its past its early growth stage and before it overly matures. As the plant becomes stemmy, fructans are stored in the stems. For my region, this means the plants need to be over 8’ tall but not seeding out. I let them graze until the grass is about 4-6” tall—any lower than that stresses the grass and concentrates sugar. I also make a chart where I hand graze starting at 5 minutes and add 5 minutes a day to a max of 4 hours if there isn’t any circumference increase in her neck crest. A horse can be fit and still have regional fat deposits that are indicative of metabolic issues. In this case, go by the condition of the crest/tail/shoulder fat deposits, NOT whether or not you can feel the ribs. Unfortunately, even with this careful management regime, because my IR horse gets cresty in the middle of a Montana winter eating hay while she is shivering, my vet is now recommending 20 min hand grazing only on grasses not actively photosynthesizing- thus early morning or after dark- and the rest of the time she has to be in a dry lot.
3. I watch the weather like a hawk. If a day is forecasted to be super-hot and sunny, I alter my turn out to early morning, or well after dark when sugars are lowest. If I can’t avoid the weather and my mare is missing all turnout, I put on a grazing muzzle and turn her out after dark for a limited time.
4. I time my turnout and set my alarm. Research [2, 3] shows that on bright sunny day’s sugar levels in grass actually peak in late afternoon (6:00 pm) since the plant has had all day to photosynthesize. I get up early and turn out, often around 6 am- then go back to bed. I bring my horses in before 9. If I cannot manage this, I try to turn out at least two hours after dark- it takes this long for the fructan levels to drop. Often, for my own sleep schedule, I might turn out two hours in early morning and the again after dinner, bringing them before bed. As a general rule, I never graze my horses between 10 am-7 pm
5. I exercise my horse as much as I can. My IR mare also has navicular, so I can’t work her too hard, but I do my very best to do some serious trot work on straight lines 3-4 times/week to get her into a serious sweat. Unfortunately there are weeks between my travel and other personal schedule I cannot do this- for example the last six months I have been dealing with recovering from major shoulder surgery and largely unable to ride. Thus, I hand walk my mare if possible at a brisk pace that gets me huffing and puffing a bit. My own veterinarian believes that regular exercise is just as important for controlling IR symptoms as regulating feed intake.
6. I feed hay- often, and in small-hole hay nets. I also weigh my hay every day. I have a set up that makes this easy, but again, it’s a daily chore that I have to invest in for the well-being of my mare. Tess strictly gets 15 pounds of food- no more, no less, broken up over 4 feedings. The small hole nets keep her trickle feeding longer than loose hay, so that we can work to avoid hind gut dysbiosis or gastric ulcers. Last summer we had a pretty nasty drought, and I literally stopped grazing my horses in early August and put them back on the dry lot. It saved my pasture and it saved my mare’s feet. She wasn’t happy about the lack of grazing, so it was my job to ride her more to help her brain.
What to do if you board? Approximately 80% of my clientele board their horses and thus are somewhat enslaved to the routine of the barn management. One suggestion is to have a discussion with your vet about what is most appropriate for your horse given your own unique situation, then approaching the barn management to seek a solution that works for everyone. Sometimes if turn out times cannot be altered, you may be able to pay a bit extra to have a grazing muzzle put on before your horse is turned out to cut down on grass intake. And while most horses start out intensely disliking their muzzle, they almost always will eventually get over it and figure out how to nibble grass regardless of the muzzle within a few days.
Yes, this is a real bother. But dealing with chronic laminitis, or a severe founder that could permanently cripple my horse is even more of a bother. I travel across the country for 10 days at a time almost every month, I have a very busy schedule and many old geriatric special needs animals. But I make it work. To grass or not to grass--- that is most certainly the question.
HOFFMAN, Rhonda M. Carbohydrate metabolism and metabolic disorders in horses. R. Bras. Zootec. [online]. 2009, vol.38, n.spe, pp. 270-276. ISSN 1806-9290
LONGLAND, A.C.; CAIRNS, A.J.; HUMPHREYS, M.O. Seasonal and diurnal changes in fructan concentration in Lolium perenne: implications for the grazing management of equines pre-disposed to laminitis. In: EQUINE NUTRITION AND PHYSIOLOGY SOCIETY SYMPOSIUM, 16. 1999, Raleigh, NC. Proceedings... Raleigh: Equine Nutrition and Physiology Society, 1999. p. 258-259
LONGLAND, A.C.; BYRD, B.M. Pasture nonstructural carbohydrates and equine laminitis. Journal of Nutritionv.136, p.2099S-2012S, 2006 (suppl.)